X-ray fluorescence (XRF) analysis is widely used for chemical analysis of materials, and one of the applications is within geochemistry, e.g. for prospecting and mining. During analysis in such applications, mineral samples are irradiated by an X-ray beam, whereby fluorescent radiation is emitted by elements contained therein. The fluorescent radiation can be analyzed, for instance, by energy dispersive analysis, whereby the energies of the photons are analyzed, and the intensity of each characteristic radiation frequency may be directly related to the amount of each element in the mineral sample. Thus, the elements present in the mineral sample, as well as the quantities of said elements, can be determined.
Traditionally in geochemistry applications, all material that were to be analyzed, such as drill cores collected during prospecting, had to be sent to a laboratory for analysis. Today however, there are instruments available to perform X-ray fluorescence analysis in situ, thereby providing a quicker response. Examples of such portable, and often handheld, instruments are commercially available from, for example, Niton.
For performing analysis in situ, there are typically two alternatives available for sample preparation. According to the first alternative, the instrument is simply directed towards the ground or against a plastic bag holding the sample, i.e. the analysis is performed without any real sample preparation. According to the second alternative, a sub-sample is picked out and packed in a cup, which is inserted in the instrument and the analysis is performed on the sample in the cup. To improve reliability of the analysis, the sample preparation here typically involves drying the sample at room temperature or in a drying chamber, grinding the sample to achieve a fine-grained structure, and then carefully packing the fine-grained sample into the cup to ensure a uniform density. However, these known methods often only provides a measure related to the surface layer of the sample, and the samples are normally required to be relatively thin, thereby providing a measure on only a very limited amount of material.
Unfortunately, the level of uncertainty associated with the in situ analysis is often considerable, and, even as the sample has been thoroughly prepared, the in situ analysis often needs to be complemented with a confirmatory laboratory analysis. This will normally reduce efficiency and slow down the field work. Further, known in situ methods are often tedious and cumbersome to use. Thus, there is a need for in situ X-ray fluorescence analysis that provides more reliable analysis and reduces the required sample preparation. There is also a need for more cost-efficient ways of providing reliable chemical material analyses on the field.